Tamper-proof caps for containers



P 20, 1966 F. G. ROBINSON 3,273,525

TAMPER-PROOF CAPS FOR CONTAINERS Filed Sept. 2, 1964 2 Sheets-$heet lINVENTOR:

R R K GUY POB/A/SOA/ p 1966 F. G. ROBINSON 3,273,525

TAMPER-PROOF CAPS FOR CONTAINERS Filed Sept. 2, 1964 2 Sheets-Sheet 2INVENTORZ FKEDERICK GU y Roan/50M QMW 4, i

A rm (r 67 United States Patent 3,273,525 TAMPER-PROOF CAPS FORCONTAINERS Frederick G. Robinson, Broad Balk, Kemp Road, Swanland, EastYorkshire, England Filed Sept. 2, 1964, Ser. No. 393,838 3 Claims. (Cl.113-121) The present invention relates to a method of and means forforming ductile tamper-proof closure caps or ferrules for containers,such as bottles, cans, tanks and drums. These closure caps ordinarilyconsist of a dished metal shell, the sides of which are either straightor deformed to provide screw threads, with the skirt depending from theside being furnished with a rolled lowermost outer peripheral projectingrim or bead which engages a collar protuberance on the neck of thebottle to secure, by overflange action, the cap to the bottle opening.The lower bead of the cap is formed at one rolled fold thereof withweakening line which comprises a series of alternate cuts or slots andblanks.

Heretofore, weakening lines have been made by rotary action around theclosure and not by a straight up and down reciprocating movementparallel to the axis of the cap. The art has long recognized the needfor accurately gauging the depth of the score lines since, if not scoreddeeply enough, the cap will not tear or will tear unequally; and if thescore lines are too deep when applied to a single thickness of metalmaterial, tearing will occur through ordinary handling thereby defeatingthe tamperproof objective of the cap. There is a strong dislike fortear-off strips scored along banding lines because of the requirementfor a very strong pull, the frequent need for a probe to start the tearand the frequent injury to the fingers and hand of the customer or user.

When closures according to the invention are initially detached frombottles by unscrewing and automatically rupturing the closure along theline of weakening provided in the bead, it will be found that theresulting raw edge with parts of the bridges remaining is tuckedinwardly out of contact with the fingers of the user. The curve left onthe cap adds strength tothe cap for its re-use.

Prior art examples of scoring a single thickness are found in US.Patents No. 2,367,317 and No. 517,580, the former patent showingweakened lines at the top edge of the lowermost skirt of the closurecap, these weakened lines made by rotary action of a cutting tool whichproduces frangible bridge adapted to be pulled away and .torn to breakthe losure.

In the US. Patent No. 2,175,350, a weakened bead edge is provided bymilling and compressing, the milling step inducing an initial weaknessby scoring and, further, by thinning the metal in the bead portion priorto folding. Upon compressional folding, there results a line of greatestweakness at the extreme outermost edge of the completely flattened,mill-weakened bead.

Closures according to the present invention are preferably sealed tobottles or like containers in well-known manner by rollingthe mouth oropen end of the skirt under a shoulder provided on the bottle and arethen provided with the line of weakening as described hereafter.However, the cap may be preformed according to the method of the presentinvention, and then sealed to the container by the conventionaloperation described above.

The object of the present invention is to provide a new and improvedmethod of forming the line of weakening in closure caps or ferrules bythe use of a non-rotatable reciprocatory press knife of predeterminedcontour. The contour of the press knife is adapted to slice completelythrough the thickness of that portion of the fold which constitutes thelowermost peripheral bead and to slice only partly through the thicknessof the adjacent fold por- 3,273,525 Patented Sept. 20, 1966 tion of thebead with the exception of blanks or bridge at equally spaced distanceswhich result from the shape of the cutting edge of the press knife. Thesecond adjacent fold of the bead is partially cut because metals vary inthickness and the depth of the cut must be calculated so that thethickness of the first portion of the fold of the bead is slicedcompletely through in order that the cap may be removed for exampleunscrewed, yet be reusable thereafter.

In accordance with the present invention, the weakening line is formedonly through one fold of the peripheral bead of the cap, e.g., throughthe lower fold of the bead, to provide an interrupted slot outcompletely through the entire thickness of the lower fold and throughonly a part of the thickness of the upper fold at its inner face. Theupper fold of the peripheral bead is thereby formed with a correspondinginterrupted cut groove of generally predetermined depth, which depth iscontrolled as a result of a single tool cutting operation; specifically,by reciprocating motion of a simple single non-rotatable tool with axialup and down cutting movement which collapses and knifes the bead, thetool consisting of a reciprocally movable non-rotatable cutter discengaging the lower surface of the bead and a stationary disc-shaped bedwhich engages the upper surface of the bead. The movable cutter memberis formed with two separate working faces; a first flat face of a shelfwhich extends radially outwardly from a location adjacent the lower,outer fold of the lowermost peripheral bead of the closure cap, and aV-shaped cross section cutting knife which is formed at the apex of acircular projection.

According to the invention, the weakening line is formed in thelowermost peripheral bead of the cap by engaging the bead between theappropriately ontoured cutting edge of a reciprocating cutting memberand the co-acting relatively stationary bed disc, so that the lower foldof the bead is cut completely through this thickness and the adjacentupper fold of the bead is cut partly through its thickness at its innerface, with the exception of blanks or bridges in both folds which resultfrom the shape of the contoured cutting edge.

Other objects of the invention will be apparent from the detaileddescription below. In order that the invention may be fully and clearlycomprehended, it is described below with reference to a preferredembodiment illustrated in the accompanying drawings, in which:

FIG. 1 is an axial section of a screw-threaded closure blank, shell orferrule whose skirt includes a rolled peripheral head or flange;

FIG. 2 is a similar view to FIG. 1 wherein there is also depicted acircular knife or cutter in engagement with the peripheral bead of theclosure blank in collaboration with a relatively stationary co-actingmember, according to the invention;

FIG. 3 is a much-enlarged view of the ringed portion A of FIG. 2;

FIG. 4 is a plan view of a fragment of the cutter shown in FIGS. 2 and 3drawn to larger scale;

FIG. 5 is an axial section of FIG. 4; and

FIG. 6 is a similar view to FIG. 1 but showing a modified form of rolledperipheral bead or flange.

Similar reference numerals refer to similar parts throughout the severalviews.

To carry out the method of the invention, there is provided a circularknife or cutter which is shown in FIGS. 2-5. The knife comprises acircular disc 1 which has a central bore of a diameter substantiallequal to the outer diameter of the skirt of the closure cap blank 2.

The closure cap blank 2 is of circular shape having a flat top andcylindrical sides of uniform thickness.

Upon one face of disc 1 there is a circumferential cutting or knife edge3 which is formed by the apex of a circular projection 4, which is ofV-shaped cross section. The continuity of the knife edge 3 isinterrupted at equally spaced intervals by a series of radial slots orgaps 5 of small width. The spacing may vary to accommodate different capmaterials.

The movable cutter member is mounted for reciprocating movement in aheadstock work-holder of conventional reciprocating machine which alsomounts the stationary oo-acting disc-shaped bed 6 which is provided witha central bore corresponding in diameter to the upper threaded portionof the skirt of the closure cap blank 2.

Discs 1 and 6 are arranged upon the actuating machine in axialalignment, together with stop mechanism for arresting the traverse ofthe disc 1 towards the relative stationary disc 6, the traverse of thedisc 1 being thereafter reversed. Preferably, the stop mechanism isadjustable.

When the bead or rolled portion 7 of a blank or shell, such as isillustrated in FIG. 1, is engaged by the cutter disc 1 with respect tothe relatively stationary disc 6 (see FIG. 2), said bead is folded tocollapse upper and lower wall portions against each other and thecutting edge 3 at the apex of the projection 4, by its axial up and downcutting movement slices completely through the lower thickness of thefold of the bead and partly through the upper thickness of the adjacentfold of the bead with the exception of bridges left by the slots or gaps5. For example, assuming that metal of .010 inch thickness is to bedealt with, the knife or cutter is set to slice completely through thethickness of the lower fold of the bead ,7 and to a sufiicient depth inthe inner face of the thickness of the upper fold of the bead to leavean uncut thickness of metal in the upper portion of .007 inch. Thus,there is left an uncut margin of .003 inch which ensures that the metalin the appropriate part of the bead has been completely out through,except for the bridges or blanks.

Thus, in a single operation and with a single tool, caps or closures canbe produced in rapid succession with extremely high degree of accuracy,whereby after application to containers the caps can easily be unscrewedto rupture the blank portions of the weakening lines. If the groove orindentation in the lower fold of the peripheral bead, except for thebridges or blanks, is not knifed through completely, the caps become unscrewable.

In order to further insure that the raw edge is completely out ofcontact with the fingers of the user, the bead or rolled portion 7 maybe turned downwardly as shown in FIG. 6.

It is therefore proposed that the same tool which collapses and effectsthe knifing may be shaped to leave the bead or rolled portion turneddownwardly; alternatively, if desired, the downward turn may be effectedas a separate operation.

It should be understood that although the bead 7 is normally collapsedand knifed in one operation, the operation can, if desired, be a twostage one, i.e., collapsed and subsequently knifed, but this is notpreferable because the objective of the invention is to achieve atamperproof cap structure at lowest cost,

The material of the cap may be any suitable ductile substance such asflexible soft metal, e.g., lead, tin, or harder metals e.g., copper,aluminum or even of flexible injection molded plastic such aspolyethylene, cellulose acetate, polycarbonate etc. All of this ductilematerials have sufficient elasticity to be springy yet are sufficientlysoft to tear readily under finger manipulation. The spacing of theinterrupted cuts permits adjustment of ease of tearing to accommodatedifference materials.

I claim:

1. In the method of manufacturing a ductile tamperproof cap which isreusable after opening, said cap having a lowermost peripheral bead anda skirt therebelow, said cap used as a closure for the mouth of acontainer having a neck and a shoulder on said neck, that improve mentin providing a weakened portion of the cap which consists of forming aninterrupted line of weakening in said rolled peripheral bead of theclosure cap on the shoulder of the neck of the bottle by the steps ofcompressing the upper and lower surfaces of said peripheral bead betweenan upper stationary pressing member and a lower non-rotatable pressingmember which is reciprocably movable toward and away from said uppermember to form upper and lower annular portions of the bead intoflattened relation and folded against each other, said lower movablemember having an outer pressing shelf and an inner knife edge, thecontinuity of said knife edge being interrupted by a series of equallyspaced radial slots to thereby cut an interrupted circular linecompletely through the entire thickness of the lower fold of saidcompressed bead and partially through the thickness of the upper fold ofsaid compressed bead by the axial up and down movement of said knifeedge, said cutting being performed by the knife edge being confined atthe juncture of the lower inner bead fold line and the dependent skirt,whereby the unscrewing of said cap automatically ruptures the closurealong the line of weakening provided at the lower fold of saidperipheral bead and the torn portions thereof curve inwardly after saidrupture.

2. The method as claimed in claim 1, wherein said cap is formed andshaped by at the lowermost peripheral bead and skirt portion with thecap over the mouth of a container having a neck and a shoulder on saidneck, and said pressing and cutting steps are carried out on the cappedcontainer.

3. The method as claimed in claim 2, wherein the compressing step andthe cutting step are carried out simultaneously.

References Cited by the Examiner UNITED STATES PATENTS 517,580 4/ 1894Livingston. 3,001,657 9/1961 Gamble 215-42 3,139,211 6/1964 Bogner220-48 CHARLES W. LANHAM, Primary Examiner.

THERON E. CONDON, Examiner.

J. B. MARBERT, Assistant Examiner.

1. IN THE METHOD OF MANUFACTURING A DUCTILE TEMPERPROOF CAP WHICH ISREUSABLE AFTER OPENING, SAID CAP HAVING A LOWERMOST PERIPHERAL BEAD ANDA SKIRT THEREBELOW, SAID CAP USED AS A CLOSURE FOR THE MOUTH OF ACONTAINER HAVING A NECK AND A SHOULDER ON SAID NECK, THAT IMPROVEMENT INPROVIDING A WEAKENED PORTION OF THE CAP WHICH CONSISTS OF FORMING ANINTERRUPTED LINE OF WEAKENING IN SAID ROLLED PERIPHERAL BEAD OF THECLOSURE CAP ON THE SHOULDER OF THE NECK OF THE BOTTLE BY THE STEPS OFCOMPRESSING THE UPPER AND LOWER SURFACES OF SAID PERIPHERAL BEAD BETWEENAN UPPER STATIONARY PRESSING MEMBER AND A LOWER NON-ROTATABLE PRESSINGMEMBER WHICH IS RECIPROCABLY MOVABLE TOWARD AND AWAY FROM SAID UPPERMEMBER TO FORM UPPER AND LOWER ANNULAR PORTIONS OF THE BEAD INTOFLATTENED RELATION AND FOLDED AGAINST EACH OTHER, SAID LOWER MOVABLEMEMBER HAVING AN OUTER PRESSING SHELF AND AN INNER KNIFE EDGE, THECONTINUITY OF SAID KNIFE EDGE BEING INTERRUPTED BY A SERIES OF EQUALLYSPACED RADIAL SLOTS TO THERBY CUT AN INTERRUPTED CIRCULAR LINECOMPLETELY THROUGH THE ENTIRE THICKNESS OF THE LOWER FOLD OF SAIDCOMPRESSED BEAD AND PARTIALLY THROUGH THE THICKNESS OF THE UPPER FOLD OFSAID COMPRESSED BEAD BY THE AXIAL UP AND DOWN MOVEMENT OF SAID KNIFEEDGE, SAID CUTTING BEING PERFORMED BY THE KNIFE EDGE BEING CONFINED ATTHE JUNCTURE OF THE LOWER INNER SEED FOLD LINE AND THE DEPENDENT SKIRT,WHEREBY THE UNSCREWING OF SAID CAP AUTOMATICALLY RUPTURES THE CLOSUREALONG THE LINE OF WEAKENING PROVIDED AT THE LOWER FOLD OF SAIDPERIPHERAL BEAD AND THE TORN PORTIONS THEREOF CURVE INWARDLY AFTER SAIDRUPTURE.